2 years ago

An element has three naturally occurring isotopes. Use the information below to calculate the weighted average atomic mass of the element, showing both the setup and the final answer for the calculation.

You're close. Just remember how to express percentages: for instance, 99% = 0.99
The masses of the isotopes are about 16-18, so you would expect the average mass to be around that too. A mass of 88 is way too high so you know you need to check your work.